Pile covering

ABSTRACT

The invention applies to sheaths for protecting underwater bodies such as piles by surrounding the body with the lower end of the sheath secured to the body and the space between the sheath and the body filled with a yieldable filler material. The improvement is that the filler material is an expandible, synthetic material expanded in place between the shell and the body to form a closed-cell foam having a snug, sealing bond with the surface of the body.

Unlted States Patent 11 1 1111 3,736,759 Bliise 1 51 June 5, 1973 541PILE COVERING 3,181,300 5/1965 Plummer ..61/54 3,661,506 5/1972 Watkins1 ..61 54 [75] Inventor g 2000 Hamburg 3,403,520 10/1968 Goodman ..61/50ermany [73] Assignee: Schlegel Manufacturing Company, FOREIGN PATENTS ORAPPLICATIONS Rochester, 279,313 10/1927 Great Britain ..61/54 22 Filed:Feb. 10,1972

Appl. No.: 225,217

[30] Foreign Application Priority Data Feb. 17, 1971 Germany ..P 21 07446.4

[52] US. Cl ..61/54 [51] Int. Cl. ..E02d 5/60 [58] Field of Search61/54, 50

[56] References Cited UNITED STATES PATENTS 1,013,758 1/1912 Fox andHatcher ..61/54 2,846,852 8/1958 Cappel ....6l/50 2,874,548 2/1959Drushel ct al. ..61/54 Primary ExaminerDavid .l. Williamowsky AssistantExaminerAlexander Grosz Attorney-Cumpston, Shaw & Stephens [57] ABSTRACTThe invention applies to sheaths for protecting underwater bodies suchas piles by surrounding the body with the lower end of the sheathsecured to the body and the space between the sheath and the body filledwith a yieldable filler material. The improvement is that the fillermaterial is an expandible, synthetic material expanded in place betweenthe shell and the body to form a closed-cell foam having a snug, sealingbond with the surface of the body.

7 Claims, 6 Drawing Figures PILE COVERING TI-IE INVENTIVE IMPROVEMENTCorrosion-resistant coatings for underwater bodies exposed to water, andespecially to sea water, are of limited value, and the cost of applyingand renewing such coatings is so high compared to their effectivenessthat it is often best to tolerate gradual degradation than to tryprotective coatings. A protective sheath offers more corrosionresistance, and US. Pat. No. 2,874,548 has suggested such a sheathformed of a pilesurrounding shell of synthetic material filled withgrease or asphalt. Grease, however, has the disadvantage of graduallyleaking into the surrounding water to cause pollution unless the shellis sealed very carefully. Also, suitable greases are quite expensive.Asphalt has the disadvantage that a mixture adjusted for high solidityand hardness does not seal to the underwater surface to be protected sothat moisture is likely to creep in between the asphalt and the pile tocause corrosion. A viscous asphalt consistency may seal better to theunderwater body, but may pollute the surrounding water, like grease,unless the shell is carefully sealed. Also, grease and asphalt are quiteheavy and require handling of large masses of material to produce suchsheaths.

The invention aims at a protective sheath for piles and other underwaterbodies to satisfactorily protect against corrosion without riskingpollution of the water and without requiring large masses of fillermaterial to be handled during installation. The invention seeks a betterand more efficient, corrosion-resistant sheath installed relativelyeasily and economically.

SUMMARY OF THE INVENTION The invention applies a water-impervious shellaround an underwater body secured to the body at the lower region of theshell and the body filled with a yieldable filler material, and improveson such an arrangement by using a filler material that is an expandiblesynthetic material expanded in place between the shell and the body toform a closed-cell foam having a snug, sealing bond with the surface ofthe body.

DRAWINGS FIGS. 1 and 2 are partially schematic, partially fragmentary,vertical longitudinal cross-section of preferred embodiments of theinventive pile covering;

FIG. 3 is a partially schematic, horizontal crosssection of a preferredembodiment of the inventive pile covering;

FIG. 4 is a partially schematic, horizontal crosssection of theinventive pile covering applied to a sheet piling; and

FIGS. 5 and 6 are partially schematic, horizontal cross-sections ofalternative preferred embodiments of the inventive pile covering.

DETAILED DESCRIPTION As shown in FIG. 1, pile l is surrounded by a shellor tube 3 of synthetic material extending down to a desired depth of,for example, 2 meters below low tide, and extending above water surface2 to above the reach of the water. Tube 3 is preferably formed of atough, elastic, thermoplastic material such as, for example, polyvinylchloride of a Shore D hardness of 82. The space between tube 3 and pile1 is filled with expanded, synthetic resin 4, such as phenol resin foamor polyurethane foam. In the bottom region of the sheath, a higherdensity foam 5 is used to secure a high quality,

dense sealing bond with the surfaces of pile l and shell 3 to providebetter protection against the penetration of water. Underlying collar orbottom plate 6 can be made permanent and sealed to pile l and shell 3,or plate 6 can be used as a mounting aid and can be removed after sheathinstallation, because high density foam 5 assured sufficient waterimpermeability.

To mount the sheath of FIG. 1, pile 1 is first cleaned in the zone to beprotected or at least in the zone to be covered by the lower end ofshell 3. Then bottom plate 6, which can be sectioned or segmented, isfitted around pile 1 and sealed to pile by sealing 7. Then, tube 3 isseated on collar 6 and sealingly connected to collar 6 by sealing 8. Theannular space between pile 1 and shell 3 is then pumped empty and dried,using conventional drying agents and means. When the surface of pile 1and the inner surface of shell 3 are sufficiently dried, the denser foam5 is formed in the bottom region of shell 3, and the lighter foam 4 oflower specific gravity is formed above high density foam 5. Foams 4 and5 both form a snug sealing bond with pile 1 and serve to provide boththe mechanical bond between pile 1 and shell 3, and the water sealingaround pile 1. Preferably, shell 3 and foam 4 are each yieldable tofollow any flexure movement of pile 1.

The light weight of expanded, synthetic filler material 4 has manyadvantages in simplifying production and installation and presentingfewer problems regarding statics. However, it has also been found thatwhen foam 4 solidifies on pile 1, it becomes sealingly bonded to thesurface of p'ile l, and the multitude of closed cells form wallssealingly bonded to the surface to be protected to form a system ofconsecutive barriers to moisture. It the outer wall of a cell breaks tolet in water, further penetration by the water is stopped by subsequentcell walls for an extremely efficient moisture barrier. In addition,foams 4 and 5 preferably contain materials capable of absorbing anywater that enters by penetration or diffusion, thus forming a dryingagent rendering such water harmless. Foams 4 and 5 can also containcorrosion inhibitors further protecting pile 1.

High-density foam 5 aids in preventing penetration of water from belowand forms an additional water or vapor barrier at the lower end of shell3. Foam 5 preferably forms a'secure sealing bond with pile l and withshell 3, and also forms a secure bond with foam 4 on top of foam 5.

The high-density foam 5 forming a moisture barrier at the bottom ofshell 3 of FIG. 1, can be supplemented or replaced by a different layercapable of forming a sealing bond with pile 1 and shell 3, and formed,for example, of a permanently plastic or permanently elastic material.Also, a highly viscous liquid can be used for a vapor barrier. Nospecial mechanical retaining means is required for a permanently elasticor a comparably stiff, but permanently plastic vapor barrier (althoughthis may be desired in some instances), but a viscous liquid vapor sealis most suitable where the lower end of the sheath is mechanicallyconnected to the underwater surface without any coarse openings allowingleakage. When the viscosity of the liquid is so high compared to thesize of any openings so that the liquid is safely contained in thesheath and cannot escape, the liquid sealant can be at a higher pressurethan the outside water pressure. Then any openings or pores in thesheath are blocked from the inside by the highly viscous liquid so thatthe water cannot enter. Since the expanded foam filler above the. liquidhas a low specific gravity, the pressure on the liquid sealant willnormally be less than, or at least no higher than the outside waterpressure. Then, it must be assumed that the water will penetrate throughopenings or pores in the sheath and cannot be excluded from the lowerjoint between the shell and the underwater body. The viscous liquid maynevertheless provide an adequate moisture barrier if the liquid has alower specific gravity than water. Then the water that penetrates willurge the sealing liquid upward against the foam which forms a mechanicalbarrier preventing the sealing liquid from rising any higher. Theviscous liquid is then capable of forming an effective barrier betweenany water penetrating the sleeve, and the foam disposed above theliquid.

If such a highly reliable moisture barrier is formed at the bottom ofthe shell between the foam and any penetrating water, then the sealingrequirements for the foam bond to the surface of the underwater body canbe reduced and relatively low-density foams are frequently adequate.

Suitable filler materials for the inventive sheath are expandedsynthetic materials that are resistent to moisture, are capable of beingapplied to the underwater surface in a liquid or pasty expandedcondition, form a closed-cell foam, andform a secure, sealing bond withthe underwater surface. Somewhat yieldable foams are preferred that areplastic or elastic enough to prevent the foam from peeling off theunderwater surface from any deformation or flexure of the sheathed body.Examples of suitable expandible materials are preferably formed ofunsaturated polyester resins such as expanded polyurethane materialscomposed of polyoles and polyisocyanates in a 1:1 ratio preferred fortheir stability and elasticity.

The preferred foams may use fillers such as expanded clay or expandedglass spheres. The preferred density of the expanded filler materialpreferably ranges from 100 to 300 kilograms per cubic meter, and theexpanded filler material, and the material of shell 3 are preferablyselected so that the foam forms a secure, sealing bond with both pile 1and shell 3. Preferably shell3 is formed of a tough, elastic materialsuch as a thermoplastic synthetic material. A preferred example ispolyvinyl chloride and copolymers with suitably adjusted hardness.

Shell 3 for protecting pilings is preferably in the form of a tube asillustrated, and it does not matter whether tube 2 is peripherallyclosed and telescoped over pile l, or whether a slit or sectioned tubeis wrapped around pile l and then closed. Shell 3 preferably hasinternal protrusions or recesses ensuring positive tension and shearresistant engagement with foam materials d and 5 whenever the sealingbond between foams 4 and 5 and shell 3 does not assure an adequate bondwithout such protrusions. Shell 3 must withstand the pressure developedin expanding foam 4 inside shell 3, and also withstand any unsymmetricalexternal load, preferably without affecting the bond between shell 3 andfiller foam 4..A firm bond of shell 3 with foam 4 is particularlyimportant where large underwater surfaces have to be protected by forcetransmission via the foam. For extruded tubes or shells 3, suitableprotrusions or recesses are preferably in the form of grooves.

Instead of using pre-formed tubes for shell 3, a shell can be made frommaterials shaped at the site. For example, a filler material can beapplied to pile ii and then a liquid or pasty material can be laid overthe filler to solidify and form shell 3. Preferred materials for such ashell are synthetic materials having a very smooth surface resistingmarine growth and reducing the risk of ice formation. A marine growthinhibitor can be included in the shell material for further protection.

The preferred method of applying the sheath of FIG.

l is to clean pile l to remove dirt and oil, attach collar 6 at thedesired depth, and seal collar 6 to pile l by sealing 7. Then tube 3 istelescoped over pile l and sealed to collar 6 by sealing 8, and theannular space between shell 3 and pile l is pumped empty, dried out, andthe desired filler material is expanded into the dry space. Preferably avapor barrier is arranged at the bottom of shell 3 such as the preferredhigh-density foam 5 as illustrated in FIG. I.

In most circumstances, it is sufficient to protect pile i only to thedepth of a few meters below the low tide surface of the water ratherthan for the entire depth of pile 1. Corrosive attack is usually limitedto the area from just below low tide to just above high tide waterlevels so this is all that needs protection.

Referring to FIG. 2, the area of pile I to be protected is surrounded byhose 13 of flexible, tough material such as a fabric-reinforcedsynthetic sheet or foil. Hose 13 is suspended at its upper end in anysuitable manner, and its lower end M is tightly bound to pile 11 withoutany coarse openings. In the space between pile land hose 13, there is abottom layer of a highly viscous liq uid 15 forming a liquid seal, asuperposed layer 16 of expanded, closed-cell elastic material. Layer I16preferably rests snugly against pile l and hose 13, but need not becompletely sealed to either. On top of layer 116, is a padding or fillermaterial 17 of expanded foam that fills hose 1 .3 and spaces it frompile l and is preferably yieldable in response to exterior mechanicalstrain.

Sealing liquid 15 preferably has a lower specific gravity than water,and it is preferably viscous enough and tough enough so that it willeither be pressed out through any gaps around lower end 114 under thepressure of superposed layers of filler material, or pressed upwardlythrough or past layer 16 under the pressure of water that may enter frombelow. Liquid 15 must be hydrophobic (water-repellent) and have a goodadhesiveness to pile l and hose 13 such as some types of oil that wouldform a safe barrier to water.

The left side of FIG. 2 shows sealing liquid 35 under a pressureexceeding that of the surrounding water with liquid 15 preventing waterfrom penetrating through any gaps around sealing zone M. The right sideof FIG. 2 shows sealing liquid 15 under pressure less than thesurrounding water so that some water 18 has entered through zone M.However, water 18 is retained by seal- .ing liquid 15, which in turn isretained by foam layer 16.

When the filler material adheres to hose i3 sufficiently, or when atension-resisting bond between shell 13 and filler 117 is not required,the inside of shell 33 can be smooth. When a firm mechanical connectionis required between shell 3 or 13 and filler foam material, the innersurface of the shell can have protrusions such as the dovetailed ribs 30illustrated in FIG. 3. Such an innerloclring interior surface for theshell is preferred when large surface areas are involved, or when thesurface to be protected is planar as in FIG. 4 which shows sheet piling20 protected by a shell 21 of synthetic material having dovetailedshaped corrugations 22 forming a positive connection between shell 21and the expanded synthetic material 23 which fills the space betweenshell 21 and sheath piling 20.

The protrusions on the shell may be large enough to serve as spacersfrom the surface to be protected as indicated in FIGS. 5 and 6. Theshell of FIG. 5 has radial ribs 24 which are spaced away from thesurrounded piling by a small clearance. Spaces between ribs 24 aresealed by an expanded synthetic resin. Ribs 26 of the embodiment of FIG.6 are fundamentally similar except for approaching the surrounded pilein a somewhat tangential rather than radial direction in the interestsof better yieldability.

Persons wishing to practice the invention should remember that otherembodiments and variations can be adapted to particular circumstances.Even though one point of view is necessarily chosen in describing anddefining the invention, this should not inhibit broader or relatedembodiments going beyond the semantic orientation of this applicationbut falling within the spirit of the invention. For example, thoseskilled in the art will appreciate the many materials and constructionsusable in various circumstances to protect underwater bodies.

I claim:

l. A pile sheathing method comprising:

a. securing a collar to said pile at the depth of said sheathing;

b. arranging a tube around said pile in spaced concentrical relationwith said pile;

c. sealing the lower end of said tube to said collar;

d. pumping the water out of the space between said tube and said pile;

e. drying said pile and the space between said pile and said tube;

f. placing an expandible, synthetic material in said space; and

g. expanding said material to form a closed-cell foam bonded to saidpile.

2. The method of claim 1 including expanding a highdensity, syntheticfoam material in the bottom of said tube, and expanding a lower densityfoam in said tube above said high-density foam.

3. The method of claim 1 including expanding a highdensity, syntheticfoam material to form a closed-cell foam sealing the lower end of saidtube to said pile.

4. The method of claim 1 including using a permanently elastic materialto form a sealing bond between the lower end of said tube and said pile.

S. The method of claim 1 including usinga permanently plastic materialto form a sealing bond between the lower end of said tube and said pile.

6. The method of claim 1 including using a waterrepellent viscous liquidmaterial to form a seal between the lower end of said tube and saidpile.

7. The method of claim 1 including binding the lower end of said tube tosaid pile to form said collar.

i l i i

2. The method of claim 1 including expanding a high-density, syntheticfoam material in the bottom of said tube, and expanding a lower densityfoam in said tube above said high-density foam.
 3. The method of claim 1including expanding a high-density, synthetic foam material to form aclosed-cell foam sealing the lower end of said tube to said pile.
 4. Themethod of claim 1 including using a permanently elastic material to forma sealing bond between the lower end of said tube and said pile.
 5. Themethod of claim 1 including using a permanently plastic material to forma sealing bond between the lower end of said tube and said pile.
 6. Themethod of claim 1 including using a water-repellent viscous liquidmaterial to form a seal between the lower end of said tube and saidpile.
 7. The method of claim 1 including binding the lower end of saidtube to said pile to form said collar.